The long way
Put the owner after the thing. This is the pattern from the names lesson.
rumah saya ‘my house’
nama kamu ‘your name’
The short way
The casual pronouns shrink into endings and attach to the noun.
rumahku ‘my house’
namamu ‘your name’
rumahnya ‘his house, her house’
These are the same register as aku and kamu: warm, informal, for people you know. With a stranger or someone older, use the long form with saya.
-nya is the busy one
-nya means his or hers, but it also marks something as specific, the way English “the” does. This is one of the highest-frequency endings in the language.
Harganya berapa? ‘How much is it?’, literally ‘its price how much’
Enaknya! ‘How tasty!’
You will meet -nya constantly before you fully understand it. For now: if a word ends in -nya and possession makes no sense, it is pointing at something specific in the situation.
Punya
For emphasis, or when the possession is the point of the sentence:
Ini punya saya. ‘This is mine.’
Kamu punya motor? ‘Do you have a motorbike?’